Generate 5G NR Waveforms

Generate standard-compliant 5G NR downlink and uplink waveforms for test and measurement, simulation, and verification using nrWaveformGenerator.

When to Use

• Generate a 5G, NR, or New Radio waveform
• Create DL waveforms with PDSCH, PDCCH, SSBurst, CSI-RS
• Create UL waveforms with PUSCH, PUCCH, SRS
• Generate NR test model (TM) or fixed reference channel (FRC) waveforms
• Configure waveform parameters: bandwidth, SCS, modulation, power levels
• Create multi-bandwidth-part waveforms

When NOT to Use

• Channel modeling or propagation — use nrCDLChannel, nrTDLChannel
• Receiver processing or decoding — use nrPDSCHDecode, nrDLSCHDecoder
• Link-level simulation end-to-end

API Choice

Do NOT use primitive-level functions (nrCarrierConfig + nrPDSCH + nrOFDMModulate) for waveform generation. These are for individual channel signal processing, not waveform construction. nrWaveformGenerator handles channel multiplexing, power scaling, and OFDM modulation correctly.

Workflow

Custom DL or UL Waveform

1. Create carrier config using the simplified constructor (R2026a+):

cfg = nrDLCarrierConfig('FR1', 20, 30);  % DL: FR1, 20 MHz, 30 kHz SCS
cfg = nrULCarrierConfig('FR1', 20, 15);  % UL: FR1, 20 MHz, 15 kHz SCS

This auto-populates SCSCarriers, BandwidthParts, SSBurst/CORESET (DL only), and a default PDSCH or PUSCH with valid parameters sized to the bandwidth.

Requires R2026a or later. On earlier releases, use the manual approach shown in the Narrow Bandwidth DL pattern — create nrDLCarrierConfig with no arguments and set SCSCarriers, BandwidthParts, and channels explicitly.

Constructor side effect: For DL, the constructor adds a dedicated SCS carrier for SSBurst if the requested SCS doesn't match the default SSB numerology. For example, nrDLCarrierConfig('FR1', 5, 30) creates a hidden 15 kHz carrier (20 RBs) for SSBurst Case A. Use manual config instead when you need exact control over the number of SCS carriers.

2. Customize channels — modify defaults or add channels:

cfg.PDSCH{1}.Modulation = '64QAM';
cfg.PDSCH{1}.Power = -3;
cfg.PDSCH{1}.DMRSPower = -6;
cfg.NumSubframes = 10;

3. Oversample (optional) — set sample rate before generation for DAC playback:

cfg.SampleRate = 245.76e6;  % Oversampled rate (default: minimum for the BW)

4. Validate — check the critical rules in the next section before generating.

5. Generate and verify — validateConfig checks structural rules but does not detect channel conflicts (e.g., overlapping PDSCH/CSI-RS, CSI-RS/SSBurst). Always call nrWaveformGenerator to catch these:

[waveform, info] = nrWaveformGenerator(cfg);

6. Visualize — open the config in the 5G Waveform Generator app:

openInGenerator(cfg);

7. Inspect output:

sr = info.ResourceGrids(1).Info.SampleRate;
grid = info.ResourceGrids(1).ResourceGridBWP;

Test Model or FRC

hNRReferenceWaveformGenerator is an example helper — set up a working directory with setupExample before use (no path modification needed):

[exDir, ~] = setupExample('5g/NRTestModelWaveformGenerationExample', fullfile(tempdir, 'tmfrc'));
workDir = fullfile(tempdir, 'myTMWaveform');
mkdir(workDir);
copyfile(fullfile(exDir, '*'), workDir);
cd(workDir);

Then generate:

wavegen = hNRReferenceWaveformGenerator('NR-FR1-TM1.1', '10MHz', '15kHz', 'FDD');
[waveform, waveinfo] = generateWaveform(wavegen);
displayResourceGrid(wavegen);

See references/test-models-and-frc.md for all valid model names and options.

Key Functions

If you need to verify property names, check valid values for a config object, or look up parameters not covered in this skill, consult the online documentation links in references/documentation-links.md.

Do not mix API levels. These primitive objects are incompatible with nrWaveformGenerator:

Critical Rules

These parameter constraints cause the most errors. Check all of them before calling nrWaveformGenerator.

NSizeGrid Must Match Channel Bandwidth

Look up NSizeGrid from the bandwidth tables. The simplified constructor (R2026a+) handles this automatically. To look up values programmatically:

nrDLCarrierConfig.FR1BandwidthTable
nrDLCarrierConfig.FR2BandwidthTable

BWP Must Fit Within SCS Carrier

NStartBWP >= NStartGrid
NStartBWP + NSizeBWP <= NStartGrid + NSizeGrid

The BWP SubcarrierSpacing must exactly match one SCS carrier's SubcarrierSpacing.

CORESET Must Fit Within BWP

Each bit set to 1 in FrequencyResources allocates 6 RBs. Total must not exceed NSizeBWP:

6 * sum(FrequencyResources) <= NSizeBWP

Max bits to set: floor(NSizeBWP / 6). For narrow bandwidths:

SSB Carrier Must Be at Least 20 RBs

The SCS carrier at the SSB numerology must have NSizeGrid >= 20.

When the user does not specify SSB parameters, choose a BlockPattern that matches the user's SCS carrier so no extra carrier is needed:

When the user explicitly requests SSB parameters that require a different SCS than the main carrier, add a dedicated SCS carrier for the SSB:

% Example: user wants Case A (15 kHz SSB) on a 30 kHz carrier
scsSSB = nrSCSCarrierConfig;
scsSSB.SubcarrierSpacing = 15;
scsSSB.NSizeGrid = 20;        % Minimum for SSB
scsSSB.NStartGrid = 0;
cfg.SCSCarriers{end+1} = scsSSB;
cfg.SSBurst.BlockPattern = 'Case A';

Disable SSBurst only when the carrier is too narrow to support any SSB (e.g., 5 MHz / 30 kHz → 11 RBs at 30 kHz, and no room for a 20-RB carrier at any SSB numerology):

cfg.SSBurst.Enable = false;

Point A Centering Constrains Multi-Carrier Layouts

When multiple SCS carriers coexist, Point A is positioned so the highest-SCS carrier is centered within the channel bandwidth. This means the lower-SCS carrier may need fewer RBs than the bandwidth table maximum. For example, 40 MHz with a full 30 kHz carrier (106 RBs) only fits 214 RBs at 15 kHz, not the table value of 216. Always call validateConfig(cfg) to check, and reduce NSizeGrid if needed.

CSI-RS Must Not Conflict With Other Channels

Within the same BWP, nrWaveformGenerator automatically reserves REs for CSI-RS — conflicts only arise between DM-RS and CSI-RS. Across different BWPs that overlap in frequency, CSI-RS defaults span the full BWP and can collide with PDSCH, PDCCH, or SSBurst. Fix with NumRB and RBOffset:

csirs1 = nrWavegenCSIRSConfig;
csirs1.BandwidthPartID = 1;
csirs1.NumRB = 106;       % Match PDSCH1 frequency region
csirs1.RBOffset = 0;
csirs1.SymbolLocations = 6;  % Avoid PDCCH symbols 0-2

CSI-RS can also conflict with SSBurst when their frequency regions overlap. This applies to any CSI-RS on any BWP — check each one. To resolve, try these approaches in order:

1. NumRB/RBOffset — narrow the CSI-RS to a frequency region that does not overlap the SSBurst carrier (works when SSBurst does not span the full bandwidth)
2. SymbolLocations — move CSI-RS to symbols not used by SSBurst
3. CSIRSPeriod — adjust periodicity and slot offset so CSI-RS avoids slots containing SSBurst

The right fix depends on the overall parameter set. Always call nrWaveformGenerator to verify no conflicts remain.

PDCCH Conflicts With PDSCH Across BWPs or RNTIs

Within the same BWP and RNTI, nrWaveformGenerator automatically reserves REs for PDCCH (via the CORESET region). PDCCH conflicts with PDSCH when:

• They are on different overlapping BWPs
• They have different RNTIs on the same BWP

To resolve, separate them in time (SymbolAllocation, SlotAllocation) or frequency (PRBSet).

PDSCH/PUSCH PRBSet Must Fit Within BWP

max(PRBSet) < NSizeBWP

For full-band allocation: PRBSet = 0:NSizeBWP-1.

PDCCH Links Through SearchSpace to CORESET

PDCCH.SearchSpaceID must reference a valid SearchSpace, which must reference a valid CORESET via CORESETID. All IDs must exist.

Patterns

Basic DL Waveform

% 20 MHz, 30 kHz SCS downlink waveform with 64QAM PDSCH
cfg = nrDLCarrierConfig('FR1', 20, 30);
cfg.PDSCH{1}.Modulation = '64QAM';
cfg.NumSubframes = 10;

[waveform, info] = nrWaveformGenerator(cfg);

% Plot resource grid
figure;
imagesc(abs(info.ResourceGrids(1).ResourceGridBWP(:,:,1)));
axis xy;
xlabel('OFDM Symbols');
ylabel('Subcarriers');
title('5G NR DL Resource Grid');
colorbar;

Basic UL Waveform

% 20 MHz, 15 kHz SCS uplink waveform with QPSK PUSCH
cfg = nrULCarrierConfig('FR1', 20, 15);
cfg.PUSCH{1}.Modulation = 'QPSK';
cfg.NumSubframes = 10;

[waveform, info] = nrWaveformGenerator(cfg);

Narrow Bandwidth DL (5 MHz, 30 kHz SCS)

Narrow bandwidths need manual config because CORESET defaults are too wide. SSBurst must be disabled here because there is no SCS carrier at the SSB numerology. (The simplified constructor avoids this by adding one automatically.)

cfg = nrDLCarrierConfig;
cfg.ChannelBandwidth = 5;

cfg.SCSCarriers = {nrSCSCarrierConfig};
cfg.SCSCarriers{1}.SubcarrierSpacing = 30;
cfg.SCSCarriers{1}.NSizeGrid = 11;   % 5 MHz at 30 kHz

cfg.BandwidthParts = {nrWavegenBWPConfig};
cfg.BandwidthParts{1}.SubcarrierSpacing = 30;
cfg.BandwidthParts{1}.NSizeBWP = 11;

% SSB needs 20 RBs — disable for 11-RB carrier
cfg.SSBurst.Enable = false;

% CORESET: max 1 group (6 RBs) for 11-RB BWP
cfg.CORESET{1}.FrequencyResources = [1 zeros(1,44)];
cfg.CORESET{1}.Duration = 2;  % Must be 2 for interleaved mapping with 1 group
cfg.PDCCH{1}.Enable = false;  % Only 2 CCEs — too few for default AggregationLevel

% PDSCH: fit within BWP
cfg.PDSCH{1}.PRBSet = 0:10;
cfg.PDSCH{1}.Power = -3;
cfg.PDSCH{1}.DMRSPower = -6;

[waveform, info] = nrWaveformGenerator(cfg);

Test Model Waveform

% NR-FR1-TM1.1 at 10 MHz, 15 kHz SCS
wavegen = hNRReferenceWaveformGenerator('NR-FR1-TM1.1', '10MHz', '15kHz', 'FDD');
[waveform, waveinfo] = generateWaveform(wavegen);
displayResourceGrid(wavegen);

To modify test model parameters (e.g., enable transport coding):

wavegen = makeConfigWritable(wavegen);
pdschArray = [wavegen.Config.PDSCH{:}];
[pdschArray.Coding] = deal(true);
wavegen.Config.PDSCH = num2cell(pdschArray);
[waveform, waveinfo] = generateWaveform(wavegen);

Multi-BWP Waveform

For waveforms with multiple bandwidth parts and numerologies, see references/multi-bwp-guidance.md.

Output Structure

[waveform, info] = nrWaveformGenerator(cfg) returns:

There is no field called ResourceGrid in info.ResourceGrids. Use ResourceGridBWP or ResourceGridInCarrier.

[waveform, waveinfo] = generateWaveform(wavegen) for hNRReferenceWaveformGenerator returns:

Conventions

• After generating a waveform, unless the user asks for something specific:
  1. Tell the user the waveform variable name and that it is in the workspace
  2. Plot the resource grid
  3. Save the generation code as a .m script and open it in the MATLAB editor with edit('scriptName.m')
• Use nrWaveformGenerator, not primitive functions (nrPDSCH + nrOFDMModulate)
• Start with the simplified constructor nrDLCarrierConfig('FR1', bw, scs) when possible
• Use nrWavegenPDSCHConfig (not nrPDSCHConfig) with nrWaveformGenerator
• Correct property names: DMRSPower (not PowerDMRS), PTRSPower (not PowerPTRS), NSizeGrid (not NRB), ChannelBandwidth (not Bandwidth)
• SCSCarriers, BandwidthParts, CORESET, PDSCH, PUSCH are cell arrays — use {}
• SSBurst is a direct object — use . not {}
• Use tiledlayout/nexttile for multi-panel figures
• Always label axes with units and include figure titles

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